Method and apparatus for mitigating contamination

Abstract

A shutter is provided near the immediate focus of a lithography apparatus in order to deflect tin debris generated by a source side of the apparatus away from a scanner side of the apparatus and towards a debris collection device. The activation of the shutter is synchronized with the generation of light pulses so as not to block light from entering the scanner side.

What is claimed is: 
     
       1. An extreme ultra violet (EUV) lithography apparatus, comprising:
 a light source that generates a light pulse and nanoparticle debris; 
 a scanner that receives the light from a junction with the light source and directs the light to a reticle stage; and 
 a shutter disposed near the junction, the shutter having at least one rotating blade that periodically blocks the junction when the light pulse is off so that the nanoparticle debris do not enter the scanner, 
 wherein the shutter comprises a plurality of rotating blades, each of the rotating blades having a width that blocks the junction during an off period of the light pulse, and 
 wherein each of the rotating blades is separated by a gap having a width that corresponds to an on period of the light pulse while the shutter is rotating. 
 
     
     
       2. The apparatus of  claim 1 , further comprising a controller configured to control a synchronization of a position of the rotating blades with a generation of the light pulse so that the rotating blades block the junction during the times when the light pulse is off. 
     
     
       3. The apparatus of  claim 1 , wherein the shutter is disposed in the scanner proximate the junction. 
     
     
       4. The apparatus of  claim 1 , further comprising an intermediate focus through which the light pulse and the nanoparticle debris flow towards the junction. 
     
     
       5. The apparatus of  claim 4 , wherein the shutter is disposed at the intermediate focus before the junction. 
     
     
       6. The apparatus of  claim 4 , wherein the intermediate focus comprises at least one nozzle for introducing a gas to direct at least some of the nanoparticle debris away from the scanner. 
     
     
       7. The apparatus of  claim 4 , further comprising a debris collector disposed at the intermediate focus that collects nanoparticle debris blocked by the shutter. 
     
     
       8. A method for extreme ultra violet (EUV) lithography, comprising:
 generating EUV light and nanoparticle debris, 
 directing the EUV light to a reticle stage; 
 blocking the nanoparticle debris with a shutter without blocking the light; and 
 catching the nanoparticle debris deflected by the shutter, 
 wherein the shutter comprises a plurality of rotating blades, each of the rotating blades having a width that blocks the junction during an off period of the light pulse, and 
 wherein each of the rotating blades is separated by a gap having a width that corresponds to an on period of the light pulse while the shutter is rotating. 
 
     
     
       9. The method of  claim 8 , wherein said catching is performed by a debris catcher disposed in an EUV source. 
     
     
       10. The method of  claim 8 , wherein the shutter is disposed in a scanner connected to the EUV source. 
     
     
       11. The method of  claim 8 , wherein the rotating blades periodically block the junction when the EUV light is not generated. 
     
     
       12. The method of  claim 11 , further comprising synchronizing a rotation of the blade with the generating EUV light. 
     
     
       13. A method of operating an extreme ultra violet (EUV) lithography system including an EUV source, comprising:
 generating a laser produced plasma (LPP) and nanoparticles in the EUV source; 
 directing light from the LPP to a scanner; 
 synchronizing a shutter disposed at a junction of the EUV source and the scanner such that a rotating blade blocks the junction during an off period of the LPP, thereby deflecting nanoparticles away from the scanner during the off period, 
 wherein the shutter comprises a plurality of rotating blades, each of the rotating blades having a width that blocks the junction during an off period of the light pulse, and 
 wherein each of the rotating blades is separated by a gap having a width that corresponds to an on period of the light pulse while the shutter is rotating. 
 
     
     
       14. The method of  claim 13 , further comprising:
 synchronizing the shutter so that a gap coincides with the junction during an on period of the LPP, thereby allowing the LPP to pass from the source to the scanner. 
 
     
     
       15. The apparatus of  claim 1 , wherein the plurality of rotating blades are connected at a central point thereby forming a fan configuration. 
     
     
       16. The apparatus of  claim 15 , wherein the plurality of rotating blades are disposed equidistantly around the central point.